Non-existance of technical support

MTN is a total no-show when it comes to technical support. I have been trying for almost 4 weeks, where my phone keeps on loosing connection to their network. After more than 20 calls to 135, two visits to MTN Bfn main branch, plenty of promises, unanswered emails, nobody calls me back and I struggle to speak to technical people. Every time I call 135 I have to start my story over again, and they try to troubleshoot my handset, which was ruled out many times. They keep on hammering on about wrong APN's, which was also ruled out. It is like the Bermuda Triangle, everything goes in, nothing comes out.....